MUSCULAR SYSTEM

anatomical terminology

? Assume the anatomical position, what do these words mean?• Inferior; superior• Proximal; distal• Medial; lateral• Posterior; anterior

TYPES OF MUSCLES1. SKELETAL: • voluntary control• striated appearance

(alternating dark & light bands)

• Tendons attach mostly to bone

• Main function is movement

TYPES OF MUSCLE2. CARDIAC:• Heart muscle,

also striated• Involuntary

control (contracts without thought)

TYPES OF MUSCLE3. SMOOTH MUSCLE:• Lines the walls of blood vessels and

hollow organs• eg. Stomach and intestines

• Involuntary movement

MUSCLE FUNCTION• Interaction of bones, skeletal

muscles & joints = MOVEMENT• Muscles move substances within the

bodyeg. Smooth muscles move food through the intestines; cardiac muscle moves blood; skeletal muscle helps venous blood return to the heart

MUSCLE FUNCTION• Postural muscles contract to stabilize

and maintain body positions• Muscles can be active even when

there is no movement at a joint

MUSCLE FUNCTION• When muscles

contract voluntarily or involuntarily (as in shivering) they can generate up to 85% of body heat

MUSCLE PROPERTIES

• CONTRACTILITY: – Ability of muscle to

contract and generate force when stimulated by a nerve

– Only muscle tissue can do this

– Muscles are usually in pairs: when one contracts the other is stretched.

MUSCLE PROPERTIES

• EXTENSIBILITY:– The ability of a muscle to be stretched

beyond its normal resting length

MUSCLE PROPERTIES

• ELASTICITY:– The muscles’ ability to return to its

original resting length after the stretch is removed

? Give an example

Using contractility,extensibility & elasticity together…

SKELTAL MUSCLE STRUCTURE

• FASCIA: – Connective tissue surrounding tissues

(as in bones & muscles)–Made of fibrous tissue, adipose tissue

(fat) & fluid– Superficial or deep– Skeletal muscles mostly work in groups– Each group (compartment) is

surrounded by fascia

SKELTAL MUSCLE STRUCTURE

• 3 layers of Fascia in each individual muscle.

• EPIMYSIUM: the outer layer covering the entire muscle

• PERIMYSIUM: surrounds bundles of muscle fibres or fascicles

• ENDOMYSIUM: surrounds the individual muscle fibres

SKELTAL MUSCLE STRUCTURE

TENDONS• Layers of Fascia continue beyond

muscle to form TENDONS.– Strong, flexible bands of fibrous connective

tissue connecting muscle to bone– Various forms: rounded cord or flat sheet– Tendons can be grouped together in a

tendon sheath. These contain synovial fluid ?Why?

– They play an important role in muscle contraction & joint movement

TENDONS

MUSCLE FIBRE• Muscles contain thousands of long,

cylindrical fibres lying parallel to each other

• Inside are small structures called myofibrils – light & dark bands

• They are arranged into units called Sarcomeres.

• Sarcomeres contain contractile proteins called Actin & Myosin

MYOFIBRIL/SARCOMERE

MUSCLE FIBRE• Muscles have a good nerve & blood

supply.• Motor neurons send messages from

CNS to the muscle• Neurons release neurostransmitters

into the blood which stimulate the muscle to contract & produce force

• Muscles have a rich network of capillaries = good damage repair

DEFINE THESE TERMS

• Define and give an example for each of the following:

• ATROPHY• HYPERTROPHY• ORIGIN• INSERTION